1. Field of the Invention
The present invention relates to a method of producing a bottle of a saturated polyester resin, which is partially crystallized to have a white pattern.
2. Description of the Prior Art
For production of frosted bottles, there have conventionally been known various methods, e.g., a method, in which a mold having its cavity formed with a rough surface is used to form a fine roughness on the surface of a bottle product, or another method, in which the bottle surface is etched after the bottle is molded. All of the prior art methods have required very complex steps so that the resultant production costs have become accordingly high. Moreover, the bottles produced according to those methods have failed to have smooth surfaces with the results that they have been difficult to clean once soiled and that they have been liable to trap dust on their surfaces. Especially in case the bottles which have their surfaces partially frosted or patterned, additional step or steps have had to be included which increase the production costs to an undesirable extent.
On the other hand, a concept of heating a bottle of a saturated polyester resin so that it may be crystallized white as a whole has been proposed in the prior art. However, this concept has never anticipated the formation of a white pattern on the surface of the bottle.